From baff6cdd3328e7b35c4e155d79105621812bceec Mon Sep 17 00:00:00 2001
From: Ricardo Cerqueira <v4l@cerqueira.org>
Date: Wed, 13 Feb 2008 22:41:15 -0300
Subject: [PATCH] V4L/DVB (7201): cx88-mpeg: Fix race condition in variable
access
There was a possible race condition in the increment/decrement of
the active device references counter.
Thanks to Trent Piepho (xyzzy@speakeasy.org) for bringing it up.
Signed-off-by: Ricardo Cerqueira <v4l@cerqueira.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
---
drivers/media/video/cx88/cx88-mpeg.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/media/video/cx88/cx88-mpeg.c b/drivers/media/video/cx88/cx88-mpeg.c
index f12733d6bf72..e357f415db06 100644
--- a/drivers/media/video/cx88/cx88-mpeg.c
+++ b/drivers/media/video/cx88/cx88-mpeg.c
@@ -615,8 +615,8 @@ static int cx8802_request_acquire(struct cx8802_driver *drv)
if (drv->advise_acquire)
{
- core->active_ref++;
mutex_lock(&drv->core->lock);
+ core->active_ref++;
if (core->active_type_id == CX88_BOARD_NONE) {
core->active_type_id = drv->type_id;
drv->advise_acquire(drv);
@@ -634,14 +634,14 @@ static int cx8802_request_release(struct cx8802_driver *drv)
{
struct cx88_core *core = drv->core;
+ mutex_lock(&drv->core->lock);
if (drv->advise_release && --core->active_ref == 0)
{
- mutex_lock(&drv->core->lock);
drv->advise_release(drv);
core->active_type_id = CX88_BOARD_NONE;
- mutex_unlock(&drv->core->lock);
mpeg_dbg(1,"%s() Post release GPIO=%x\n", __FUNCTION__, cx_read(MO_GP0_IO));
}
+ mutex_unlock(&drv->core->lock);
return 0;
}
--
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